Sensing method for biopolymers and sensing device therefor

Abstract

A sensing method for biopolymers by detecting the magnetic signal generated from a labeled biopolymer under AC magnetic field with thermo-responsive magnetic nano particles as label having a critical solution temperature across which the particles have the ability to aggregate or disperse with cooling or heating.

What is claimed is: 
     
       1. A sensing method for biopolymers by detecting the magnetic signal generated from a labeled biopolymer under AC magnetic field with the use of thermo-responsive magnetic nano particles as label, comprising the steps of;
 using the thermo-responsive magnetic nano particles having a critical solution temperature across which the particles have the ability to aggregate or disperse with cooling or heating; 
 binding a ligand for a target biopolymer to said thermo-responsive magnetic nano particles; 
 labeling the target biopolymer in solution with said thermo-responsive magnetic nano particles using a biopolymer reaction; 
 adding ligand free thermo-responsive magnetic nano particles; 
 keeping the solution temperature at which said thermo-responsive magnetic nano particles aggregate; 
 
       applying AC magnetic field after aggregating the thermo-responsive magnetic nano particles and enlarging the aggregate of said thermo-responsive magnetic nano particles; and
 obtaining a larger magnetic signal at the time of measurement as compared with the magnetic signal obtained when said ligand free thermo-responsive magnetic nano particles are not added. 
 
     
     
       2. The sensing method for biopolymers according to  claim 1 , wherein;
 binding an antibody for an antigen to said thermo-responsive magnetic nano particles; 
 labeling said antigen in solution with the thermo-responsive magnetic nano particles bound with the antibody using an antigen antibody reaction; 
 adding the thermo-responsive magnetic nano particles which are not bound with antibody; 
 keeping the solution temperature at which said thermo-responsive magnetic nano particles aggregate; 
 applying AC magnetic field after aggregating the thermo-responsive magnetic nano particles and enlarging the aggregate of said thermo-responsive magnetic nano particles; 
 obtaining a larger magnetic signal at the time of measurement as compared with the magnetic signal obtained when thermo-responsive magnetic nano particles, which are not bound with antibody, are not added; and 
 detecting said antibody. 
 
     
     
       3. The sensing method for biopolymers according to  claim 1 , wherein;
 labeling a single stranded DNA complementary to a target single stranded DNA with said thermo-responsive magnetic nano particles; 
 hybridizing said complementary DNA with said target single stranded DNA in solution; 
 adding the thermo-responsive magnetic nano particles which are not labeled with said complementary DNA just before the measurement of magnetic signal; 
 keeping the solution temperature at which said thermo-responsive magnetic nano particles aggregate; 
 applying AC magnetic field after aggregating the thermo-responsive magnetic nano particles and enlarging the aggregate of said thermo-responsive magnetic nano particles; 
 obtaining a larger magnetic signal at the time of measurement as compared with the magnetic signal obtained when the thermo-responsive magnetic nano particles, which are not bound with said complementary DNA, are not added; and 
 detecting said target single stranded DNA. 
 
     
     
       4. The sensing method for biopolymers according to any one of  claims 1  to  3 , wherein said thermo-responsive magnetic nano particles comprise a thermo-responsive polymer and magnetic nano particles;
 said thermo-responsive polymer is the polymer having a lower critical solution temperature or an upper critical solution temperature; 
 said magnetic nano particles are the particles comprising a polyhydric alcohol and a magnetic material; 
 
       the polymer having a lower critical solution temperature is the polymer comprising at least one monomer component which is selected from the group consisting of N-n-propylacrylamide, N-isopropylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, N-acryloylpyrrolidine, N-acryloylpiperidine, N-acryloylmorpholine, N-n-propylmethacrylamide, N-isopropylmethacrylamide, N-ethylmethacrylamide, N,N-dimethylmethacrylamide, N-methacryloylpyrrolidine, N-methacryloylpiperidine, and N-methacryloylmorpholine;
 the polymer having an upper critical solution temperature is the polymer comprising at least one monomer component which is selected from the group consisting of acrylamide, acetylacrylamide, biotinol acrylate, N-biotinyl-N′-methacryloyltrimethyleneamide, N-acryloylglycinamide, acryloylsarcosinamide, methacryloylsarcosinamide, acryloylnipecotamide, and acryloylmethyluracil; said polyhydric alcohol is at least one alcohol component which is selected from the group consisting of dextran, polyvinyl alcohol, mannnitol, and sorbitol; and 
 the magnetic material is at least one kind of material which is selected from the group consisting of oxide magnetic materials and metallic magnetic materials. 
 
     
     
       5. The sensing method for biopolymers according to  claim 4 , wherein the thermo-responsive magnetic nano particles comprise a thermo-responsive polymer and magnetic nano particles;
 the thermo-responsive polymer comprising the polymer obtained from N-isopropylacrylamide or from N-acryloylglicinamide; and 
 the magnetic nano particles are the particles comprising dextran and ferrite.